In a medium bowl combine the dry ingredients; flour, salt, baking powder, and nutmeg. Keep it aside.
In a separate bowl, beat the butter and sugar to a sandy texture. Add in the egg yolks and beat until pale and light.
Add the vanilla extract and sour cream and beat until well combined. Slowly add the dry ingredients in batches. Mix it well. The dough might be sticky.
Cove the dough with plastic wrap and refrigerate for 1 hour.
Meanwhile, prepare the glaze by combining the mentioned ingredients on the “for the glaze” section in a bowl until smooth. If the glaze is too thick, thin it out by adding a couple of tablespoons of additional hot water and keep it aside.
Remove the dough and place it on a silicon mat. Add some extra flour if the dough is sticky still. With the help of the rolling pin spread the dough to ½ inch thickness.
Use a doughnut cutter or cookie cutters cut out donut shapes. Reuse the remaining dough to spread again and cut it out into donut shapes.
Place the donuts on parchment paper and freeze them for 10 minutes.
In a heavy bottom wok heat the oil; slowly add the donuts and fry them for 2-3 minutes until they are golden by flipping on both sides. Drain the excess oil and remove the donuts.
Dip the donuts completely with the glaze one by one and place them on a rack for 15 minutes. Once the glaze is set serve the donuts.